We report on the progressive investigation of techniques for supporting interactive query reformulation in the TREC Interactive Track task. Two major issues were explored over four successive years: various methods of term suggestion; and, interface design to support different system functionalities. Each year's results led to the following year's investigation, with respect to both of these major issues. This paper presents first the general motivation for the entire series of studies; then an

more »

... overview of each year's investigation, its results, and how they influenced the next year's investigation. We discuss what we believe has been learned through this series of investigations about effective term suggestion, usable and useful interface design, and the relationships between these two in support of the TREC Interactive Track task. We conclude with some comments about the general methodology which we employed over this series of studies, and its relevance to the development and evaluation of interactive information retrieval systems in general.